(1) Field of the Invention
The present invention pertains to an air flow control mechanism for a multi-channel air conveyor that enables the flow rate of air ejected from air outlets of inner channels of the air conveyor to be adjusted without changing the flow of air ejected from air outlets of the outer channels of the air conveyor.
(2) Description of the Related Art
Air conveyors are typically employed in the rapid transport of empty plastic bottles of the type having an annular rim or a neck ring at the top of the bottle neck. A typical air conveyor includes a pair of flanges that are spaced from each other defining an elongated slot between the flanges. The slot between the spaced flanges defines a conveyor path or a channel of the air conveyor. The lateral spacings between the pairs of flanges of the conveyor channel is sufficiently large to enable a portion of the bottle neck just below the neck ring to pass through the spacing between the flanges with the bottle suspended from the top surfaces of the pairs of flanges by the neck ring resting on the top surfaces. A series of air jets or air outlet orifices are arranged along the longitudinal lengths of the pairs of flanges positioned above and/or below the flanges. A plenum of the air conveyor supplies a flow of air to the air outlet orifices. The air outlet orifices on the opposite sides of the channel are oriented so that air supplied from the plenum and ejected from the air outlet orifices will contact the plastic bottles and push the bottles along the conveyor path of the channel defined by the elongated slots between the pairs of flanges with the neck rings of the bottles sliding along the top surfaces of the pairs of flanges.
For air conveyors of considerable longitudinal length, conveyor sections are connected end-to-end so that the pairs of flanges of one conveyor section are aligned with the pairs of flanges of the adjacent conveyor section and the pairs of flanges, aligned end-to-end, define the conveyor path or the channel of the air conveyor.
A multi-channel air conveyor includes a multiple of channels and their associated pairs of flanges arranged laterally side-by-side, with the multiple of pairs of flanges extending longitudinally along the length of the multi-channel air conveyor, thereby defining a multiple of side-by-side conveyor paths or channels. Like a single channel air conveyor, a multi-channel air conveyor includes a series of air jets or air outlet orifices that are arranged along the longitudinal lengths of each of the pairs of flanges that define the channels of the multi-channel air conveyor. A plenum of the air conveyor supplies the flow of air to the air outlet orifices of the multiple channels.
For manufacturing convenience and to reduce costs, all of the air outlet orifices of each of the channels of a multi-channel air conveyor are typically supplied with a flow of air from the same air plenum positioned above the channels. The air outlet orifices on the opposite sides of each of the channels are oriented so that air supplied from the plenum and ejected from the air outlet orifices will contact the plastic bottles, pushing the bottles along the air conveyor channels defined by the pairs of conveyor flanges with the neck rings of the bottles sliding along the top surfaces of the pairs of flanges.
A drawback encountered with multi-channel air conveyors is that the side-by-side positioning of the slots or channels allows the interaction of jets of air ejected from the air outlet orifices of adjacent air conveyor channels. This is most evident in the inner air conveyor channels that are positioned between the outer pair of air conveyor channels that extend along the laterally opposite sides of the multi-channel conveyor. The air outlet orifices spacially arranged along the longitudinal lengths of the air conveyor channels are dimensioned to push plastic bottles along the channels at a desirable speed and at a desirable orientation of the bottles relative to the channels and the flanges defining the channels. However, with multi-channel air conveyors having a plurality of adjacent conveyor channels and their associated pairs of outlet orifices, the air ejected from pairs of outlet orifices along one conveyor channel will influence the air ejected from the air outlet orifices along an adjacent conveyor channel. This is most evident along the inner air conveyor channels or those channels that are positioned between the pair of air conveyor channels that extend along the laterally opposite sides of the multi-channel air conveyor. Each of the inner air conveyor channels will convey bottles that are pushed along the channels not only by the force of air ejected from the rows of air outlet orifices of the particular inner channel, but also by the force of some of the air ejected from the air outlet orifices of adjacent air conveyor channels. The outer air conveyor channels that extend along the laterally opposite sides of the multi-channel air conveyor are only influenced by air ejected from the air outlet orifices of the adjacent inner air conveyor channel. Therefore, the effect of air ejected from adjacent air conveyor channels on the bottles conveyed by the outer pair of air conveyor channels of the multi-channel air conveyor is not appreciable. However, the plastic bottles conveyed by the inner air conveyor channels are subjected to not only the force of air ejected from the air outlet orifices arranged along the particular inner air channel, but also a portion of the air ejected from air outlet orifices of air conveyor channels on both sides of the particular inner channel. This results in the bottles being conveyed along the inner air conveyor channels at a greater speed than intended and at a greater speed than the bottles conveyed along the outer air conveyor channels.
In addition, in single channel air conveyors it may be desirable to control the flow of air ejected from the air outlet orifices of a section of the channel to control the speed of bottles conveyed through the channel or to control the pressure exerted on a forward most bottle or bottles of a slug or series of bottles accumulated in the particular air conveyor channel. It may also be desirable to quickly adjust the flow of air ejected from air outlet orifices of the air conveyor channel depending on what size of bottle is being conveyed through the air conveyor channel.
What is needed to overcome these problems associated with single channel or multi-channel air conveyors is a mechanism by which the flow of air ejected through the air outlet orifices of the air conveyor channels of an air conveyor can be adjusted and reduced to thereby control the speed of the bottles conveyed through the air conveyor channels.
The air conveyor of the present invention overcomes the above described disadvantage associated with multi-channel air conveyors by providing an adjustable air flow control mechanism for a multi-channel air conveyor that can adjust the flow of air ejected from the air outlet orifices of the inner channels. In the preferred embodiment, the air flow control mechanism for the multi-channel air conveyor is employed with a multi-channel air conveyor of the type described earlier. The multi-channel air conveyor is assembled in sections. Each section has a longitudinal length along which the multi-channels extend and a lateral width across which the multi-channels are arranged side-by-side. A base of the air conveyor is connected to an air plenum that extends across the top of the base. Pluralities of pairs of side walls extend downwardly from the base and support pairs of mutually opposed, laterally spaced flanges. The spacings between the pairs of flanges define the conveyor slots or the conveyed paths of the air channels of the multi-channel air conveyor. Air ducts extend through each of the side walls between air inlet orifices that open through the top of the base and air outlet orifices that open near the bottoms of the side walls. The air outlet orifices are oriented to direct a flow of air ejected from the air outlet orifices toward the slot defined by the pairs of flanges supported between each pair of side walls. Thus, air ejected from the air outlet orifices of each of the air conveyor channels will push plastic bottles supported by their neck rings from the opposed pairs of flanges of each air conveyor channel downstream through the air conveyor channel. As stated above, the speed at which the plastic bottles are pushed down the air conveyor channels is determined by the force of the air ejected from the air outlet orifices of each of the channels.
The multi-channel air conveyor of the invention differs from prior art multi-channel air conveyors in that it includes an adjustable air flow control mechanism. In the preferred embodiment, the control mechanism only adjusts the air flow of the inner air conveyor channels. However, although the adjustable air flow control mechanism is described as adjusting the air flow of the inner air conveyor channels, a similar mechanism could be used to adjust the air flow of the outer air conveyor channels independently of the inner air conveyor channels. In addition, the air flow control mechanism of the invention may be employed in adjusting the air flow of single channel air conveyors to adjust the speed of bottles conveyed through these air conveyors and to adjust the force exerted on the forward most bottles of a slug or sequence of bottles that are temporarily held back in a section of an air conveyor, whether a single channel or multi-channel air conveyor.
To adjust the flow of air ejected from the air outlet orifices of the inner air channels so that the speed of bottles conveyed through the inner air channels substantially matches that of bottles conveyed through the outer air channels, the adjustable air flow control mechanism of the invention employs a throttle plate that overlays a portion of the top of the base inside the air plenum. In this particular application, the plate has a lateral width that overlays only the inner air channels of the air conveyor. However, as explained earlier, it could also overlay outer channels to adjust air flow through these channels. The plate lateral width does not extend over the outer channels of the air conveyor and therefore operation of the adjustable air flow control mechanism will not change the flow of air through the air outlet orifices of the outer channels of the air conveyor. The plate is provided with longitudinal rows of throttle openings that are arranged on the plate to correspond to the positions of the air inlet orifices of the inner air channels of the conveyor. The plate can slide across the interior surface of the air plenum between first and second positions of the plate.
In the first position of the plate, the throttle openings in the plate are aligned with the air inlet orifices of the inner air channels. In this first position of the plate it does not restrict the flow of air supplied by the air plenum through the air inlet orifices of the inner air channels. The air outlet orifices of the inner air channels as well as the air outlet orifices of the outer air channels will eject substantially the same flow of air. However, as the plate is moved from its first position toward its second position, the throttle openings of the plate gradually move away from their alignment with the air inlet orifices of the inner air channels and progressively restrict the flow of air supplied by the air plenum to the air inlet orifices of the inner air channels. This reduces the flow of air ejected from the air outlet orifices of the inner air channels. In this manner, the adjustable air flow control mechanism can be used to adjust the air flow ejected from the air outlet orifices of the inner air channels so that the speed of plastic bottles conveyed through the inner air channels can be substantially matched to that of the speed of bottles conveyed through the outer air channels.
The throttle plate of the air control mechanism is moved between its first and second positions relative to the air inlet orifices of the air channels by a manually operated transfer assembly at one end of the throttle plate. The transfer assembly includes a shaft mounted for rotation to the air plenum that extends laterally across the air plenum. The shaft has a manual handle mounted to one end of the shaft outside the plenum. Inside the plenum, a generally cylindrical cam is mounted eccentrically on the shaft. A cam receiver block is mounted on the throttle plate. The cam receiver block has a cam slot and the cam mounted on the shaft is received in the cam slot. Manual rotation of the manual handle in opposite directions causes the cam to slide in the cam slot in opposite directions which in turn causes the throttle plate to move reciprocally between its first and second positions relative to the air inlet orifices of the inner air conveyor channels. In this manner, the positions of the throttle openings of the throttle plate are adjusted between their first and second positions relative to the air inlet orifices of the inner conveyor slots, thereby adjusting the flow of air through the air ducts and air outlet orifices of the inner air conveyor channels.
The opposite end of the throttle plate is held down against the interior surface of the air conveyor base by an idler shaft. The throttle plate can be constructed of one continuous longitudinal plate, or alternatively constructed of separate plate sections connected end-to-end. In addition, air flow control mechanisms of adjacent air conveyor sections that are connected end-to-end can be interconnected by chain and sprocket connections so that controlling the positioning of one throttle plate in one conveyor section will also control the positioning of a throttle plate in an adjacent conveyor section.